How does Chuck Palahmiuk create interesting characters in the novel Fight Club?

The author of Fight Club, Chuck Palahnuik created several characters that constantly surprise the reader with their complexity and unpredictable behaviors, all of which causes them to become more interesting. 
The main character, also the narrator, is interesting for multiple reasons: first, he appears to be incredibly bored by his mundane life and this is only made worse by his chronic narcolepsy. For the reader, his mundane life is not interesting, but his view of it is. He seems very dissatisfied with his life and trapped by it. Many readers might find themselves in life situations where they also feel trapped and as if they are serving no real purpose. They may feel lost like the narrator, making him an interesting character to them. His narcolepsy makes him interesting because this is not a common disorder to have and the consequences of falling asleep at random moments can have humorous and damaging effects, which also makes the character more interesting.
Second, the narrator is heavily influenced by other people, like Tyler and Marla. For instance, right away in Ch. 1 he notes, "I know this because Tyler knows this." He does not question Tyler's knowledge and adopts it as his own. This makes the narrator interesting because the reader has to wonder what will happen to him as a result of blindly following someone else. As the novel progresses, the narrator becomes more and more influenced by Tyler's beliefs and actions, to the point where much of the narrator's own identity becomes lost.
Tyler Durden is interesting because his behavior is so unpredictable. The very nature of his personality seems to be that of rebellion, but it is presented in a way that makes it looks as though he is trying to reach a higher state of being. He convinces the narrator of this as well, and is constantly trying to get the narrator to "hit bottom" so that he can finally restart his life and find "zen." However his behavior is anything but zen-like. He and the narrator start Fight Club, but later Tyler begins Project Mayhem, the purpose of which is to vandalize properties. Tyler's personality is extreme, which makes him interesting. He is so far outside of what one would consider normal or civilized society that he appears to be irrational. This causes the reader to wonder what he will do next, why he will do it, and how it will affect everyone around him—especially the narrator.
The author's dynamic, unpredictable, and complex characters are incredibly interesting because it is difficult for the reader to guess what will happen next or assume their outcome.